Common Name:

General Information

Arisaema costatum is a herbaceous perennial plant growing from a tuber that is usually renewed seasonally. A single leaf, 30 - 50cm long is produced and a flowering stem 25 - 45cm tall. The tuber also produces some tubercles around its base - these become separated from the old tuber at the end of the season, growing on in subsequent years to form new plants[].
The plant is sometimes harvested from the wild for local use as a food - mainly when little else is available.

Known Hazards

The plant contains calcium oxylate crystals. These cause an extremely unpleasant sensation similar to needles being stuck into the mouth and tongue if they are eaten but they are easily neutralized by thoroughly drying or cooking the plant or by steeping it in water.

Botanical References

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Range

E. Asia - Himalayas in central and eastern Nepal, southern Tibet.

Habitat

Wet cool woodlands and cliffs, often forming large colonies. Shrubberies, 2,000 - 2,600 metres[]. Grasslands in forest areas at elevations of 2,300 - 2,400 metres[].

Properties

Edibility Rating
Habit	Perennial
Height	0.60 m
Pollinators	Flies
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Arisaema costatum is is only hardy outdoors in the milder areas of the temperate zone[].
Prefers a cool peaty soil in the bog, woodland garden or a sheltered border in semi-shade[]. Prefers a loamy or peaty soil[] and will tolerate a sunny position if the soil is moist but not water-logged and the position is not too exposed[, ].
Tubers should be planted about 15cm deep[]. Only plant out full sized tubers and mulch them with organic matter in the winter[]. Plants multiply quickly once they are established[]. Plants need protection from slugs[].
This species has very large leaves, to 40cm long[].
Most species in this genus are dioecious, but they are sometimes monoecious and can also change sex from year to year. The plant is paradioecious. The sex depends on nutrition and is therefore variable from one year to another[]. Smaller plants produce only staminate flowers, whilst larger plants produce either staminate and pistillate flowers simultaneously or pistillate flowers only. Changes in gender expression are directly correlated with size and are also influenced by the environment in which the plants are growing. Reversions in phenotypic gender have been experimentally induced by such factors as removing leaf area or changing soil nutrient levels[].

Edible Uses

Root - cooked. It is boiled, dried and then ground into a powder[, ]. The tuber is 3 - 5cm in diameter[]. Some caution is advised, see the notes above on toxicity.

Medicinal

None known

Other Uses

None known

Propagation

Seed - best sown as soon as it is ripe in a shady position in a cold frame[]. Stored seed remains viable for at least a year and can be sown in spring in the greenhouse but it will probably require a period of cold stratification. Germination usually takes place in 1 - 6 months at 15°c[]. When large enough to handle, prick the seedlings out into individual pots and grow them on in light shade in the greenhouse for at least a coupe of years until the corms are more than 20mm in diameter. Plant out into their permanent positions whilst they are dormant.
Division of tubers when the plant dies down in late summer.